On my offset smoker/grill, I have moved my exhaust many times, I lowered the fire box, made a 1/4 plate diverter to turn it into a reverse flow, that took almost 2 hours to get the whole smoker up to temp. Cut all that out, anyway after many trials with plates etc, I made a small expanded metal box about 3 in wide, 7 inches long and 6 inches high that I placed at the opposite end of the main firebox ( make a coal basket for the main firebox!!! out of expanded metal) moved the exhaust back to the opposite end of the main firebox, made a cheap aluminum flashing deflector for the inside of the exhaust to block direct flow. A 1 1/2 hole in the grill at the opposite end of the main firebox at the very side bottom and used more flashing to make a simple air shut off flapper. Putting 4 or 5 lit coals on top of the small firebox that is full of unlit coals, this will burn for 3 to 4 hrs depending before needing more coals. With the main firebox set as normal and using the small firebox I had temps within 10 across the smoker. Real windy days I had to move the smoker so the wind did not blow straight in from either end. And you can still use it as a grill. the ash from the small firebox falls where the grill ash goes..easy to clean. Gave that smoker to a friend to learn to smoke, then I built a bullet smoker, he gave the offset to his dad who still uses it, and he now has one of my UDS smokers. Sorry, I never got pics, but If you need more info let me know.